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diff --git a/pipermail/pycrypto/2014q2/000793.html b/pipermail/pycrypto/2014q2/000793.html new file mode 100644 index 0000000..5d89552 --- /dev/null +++ b/pipermail/pycrypto/2014q2/000793.html @@ -0,0 +1,175 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> +<HTML> + <HEAD> + <TITLE> [pycrypto] Verify DSA bytestring signature + </TITLE> + <LINK REL="Index" HREF="index.html" > + <LINK REL="made" HREF="mailto:pycrypto%40lists.dlitz.net?Subject=Re%3A%20%5Bpycrypto%5D%20Verify%20DSA%20bytestring%20signature&In-Reply-To=%3C2C34FE60-DE8F-4F3E-B305-6397882BFC09%40ml1.net%3E"> + <META NAME="robots" CONTENT="index,nofollow"> + <style type="text/css"> + pre { + white-space: pre-wrap; /* css-2.1, curent FF, Opera, Safari */ + } + </style> + <META http-equiv="Content-Type" content="text/html; charset=us-ascii"> + <LINK REL="Previous" HREF="000792.html"> + <LINK REL="Next" HREF="000794.html"> + </HEAD> + <BODY BGCOLOR="#ffffff"> + <H1>[pycrypto] Verify DSA bytestring signature</H1> + <B>Winston Weinert</B> + <A HREF="mailto:pycrypto%40lists.dlitz.net?Subject=Re%3A%20%5Bpycrypto%5D%20Verify%20DSA%20bytestring%20signature&In-Reply-To=%3C2C34FE60-DE8F-4F3E-B305-6397882BFC09%40ml1.net%3E" + TITLE="[pycrypto] Verify DSA bytestring signature">winston at ml1.net + </A><BR> + <I>Sun Apr 6 15:49:47 PDT 2014</I> + <P><UL> + <LI>Previous message: <A HREF="000792.html">[pycrypto] Verify DSA bytestring signature +</A></li> + <LI>Next message: <A HREF="000794.html">[pycrypto] Verify DSA bytestring signature +</A></li> + <LI> <B>Messages sorted by:</B> + <a href="date.html#793">[ date ]</a> + <a href="thread.html#793">[ thread ]</a> + <a href="subject.html#793">[ subject ]</a> + <a href="author.html#793">[ author ]</a> + </LI> + </UL> + <HR> +<!--beginarticle--> +<PRE>The signature is created using the openssl(1) command-line tool like this: + +openssl dgst -sha1 -binary < "$RELEASE_ARCHIVE" \ +|<i> openssl dgst -dss1 -sign "$DSA_PRIVKEY" \ +</I>|<i> openssl enc -base64 +</I> +It verifies correctly using this command-line: + +echo "$SIGNATURE” | openssl enc -base64 -d > /tmp/decoded_signature +openssl dgst -sha1 -binary < "$RELEASE_ARCHIVE" > /tmp/release_archive_sha1 +openssl dgst -dss1 -verify "$DSA_PUBKEY" -signature /tmp/decoded_signature /tmp/release_archive_sha1 + +After I wrote my email, I dug around for awhile. After a lot of research I learned +about ASN.1 DER’s usage in Dss-Sig-Value (<A HREF="http://www.ietf.org/rfc/rfc2459.txt">http://www.ietf.org/rfc/rfc2459.txt</A>). I +wrote this code that appeared to decode my Base64 encoded signature correctly (I +checked against <A HREF="http://lapo.it/asn1js/">http://lapo.it/asn1js/</A>): + +def decode_DSA_signature(signature): + raw_signature = base64.b64decode(signature) + der = DerSequence() + der.decode(raw_signature) + return (der[0], der[1]) + +Unfortunately .verify() returns False on correctly verified signature and hash +pairs. I am using this new function like so: + + +def validate(dsa_pubkey, signature, zipfile): + with open(dsa_pubkey, 'rb') as f: + pubkey = DSA.importKey(f.read()) + with open(zipfile, 'rb') as f: + h = SHA1.new() + h.update(f.read()) + zipfile_digest = h.digest() + signature = decode_DSA_signature(signature) + + return pubkey.verify(zipfile_digest, signature) + +Maybe there is a problem with PyCrypto DSA and my environment? +>>><i> sys.version +</I>'2.7.6 (default, Feb 7 2014, 12:51:34) \n[GCC 4.2.1 Compatible Apple LLVM 5.0 (clang-500.2.79)]' + +For the time being I’m invoking openssl(1) for this task. + +Thank you for the reply! +Winston Weinert + + +On Apr 6, 2014, at 4:50, Legrandin <<A HREF="http://lists.dlitz.net/cgi-bin/mailman/listinfo/pycrypto">helderijs at gmail.com</A>> wrote: + +><i> How was the signature created exactly? +</I>><i> +</I>><i> The .verify() method of a DSA object requires two integers, and there are several ways to encode them into a bytestring. It's very hard to guess the correct one for your case. +</I>><i> +</I>><i> FYI, there is a long standing pull request I created to add a saner DSA API: +</I>><i> +</I>><i> <A HREF="https://github.com/dlitz/pycrypto/pull/53">https://github.com/dlitz/pycrypto/pull/53</A> +</I>><i> +</I>><i> The verification method accepts DER or big-endian encoded signatures. +</I>><i> +</I>><i> +</I>><i> +</I>><i> 2014-04-05 21:03 GMT+02:00 Winston Weinert <<A HREF="http://lists.dlitz.net/cgi-bin/mailman/listinfo/pycrypto">winston at ml1.net</A>>: +</I>><i> Hello, +</I>><i> +</I>><i> I noticed in Git there is a “verify” method on Crypto.PublicKey.DSA. How do +</I>><i> I go about using this method? It wants a tuple, but unsure how to create +</I>><i> the appropriate tuple from my bytestring (which is decoded base64 text). +</I>><i> This is git revision 2d1aecd. The relevant code and error: +</I>><i> +</I>><i> Code: +</I>><i> +</I>><i> def validate(dsa_pubkey, signature, zipfile): +</I>><i> with open(dsa_pubkey, 'rb') as f: +</I>><i> pubkey = DSA.importKey(f.read()) +</I>><i> with open(zipfile, 'rb') as f: +</I>><i> h = SHA1.new() +</I>><i> h.update(f.read()) +</I>><i> zipfile_digest = h.digest() +</I>><i> decoded_signature = base64.b64decode(signature) +</I>><i> +</I>><i> return pubkey.verify(zipfile_digest, decoded_signature) +</I>><i> +</I>><i> Error: +</I>><i> +</I>><i> Traceback (most recent call last): +</I>><i> File "sparkle_tool.py", line 67, in <module> +</I>><i> validate_files(appcast, dsa_pubkey) +</I>><i> File "sparkle_tool.py", line 55, in validate_files +</I>><i> if validate(dsa_pubkey, signature, local_file): +</I>><i> File "sparkle_tool.py", line 33, in validate +</I>><i> return pubkey.verify(zipfile_digest, decoded_signature) +</I>><i> File "/home/winston/jobber/venv/local/lib/python2.7/site-packages/Crypto/PublicKey/DSA.py", line 222, in verify +</I>><i> return pubkey.pubkey.verify(self, M, signature) +</I>><i> File "/home/winston/jobber/venv/local/lib/python2.7/site-packages/Crypto/PublicKey/pubkey.py", line 126, in verify +</I>><i> return self._verify(M, signature) +</I>><i> File "/home/winston/jobber/venv/local/lib/python2.7/site-packages/Crypto/PublicKey/DSA.py", line 240, in _verify +</I>><i> (r, s) = sig +</I>><i> ValueError: too many values to unpack +</I>><i> +</I>><i> Thanks a bunch! +</I>><i> — +</I>><i> Winston Weinert +</I>><i> <A HREF="http://lists.dlitz.net/cgi-bin/mailman/listinfo/pycrypto">winston at ml1.net</A> +</I>><i> _______________________________________________ +</I>><i> pycrypto mailing list +</I>><i> <A HREF="http://lists.dlitz.net/cgi-bin/mailman/listinfo/pycrypto">pycrypto at lists.dlitz.net</A> +</I>><i> <A HREF="http://lists.dlitz.net/cgi-bin/mailman/listinfo/pycrypto">http://lists.dlitz.net/cgi-bin/mailman/listinfo/pycrypto</A> +</I>><i> +</I>><i> _______________________________________________ +</I>><i> pycrypto mailing list +</I>><i> <A HREF="http://lists.dlitz.net/cgi-bin/mailman/listinfo/pycrypto">pycrypto at lists.dlitz.net</A> +</I>><i> <A HREF="http://lists.dlitz.net/cgi-bin/mailman/listinfo/pycrypto">http://lists.dlitz.net/cgi-bin/mailman/listinfo/pycrypto</A> +</I> +</PRE> + + +<!--endarticle--> + <HR> + <P><UL> + <!--threads--> + <LI>Previous message: <A HREF="000792.html">[pycrypto] Verify DSA bytestring signature +</A></li> + <LI>Next message: <A HREF="000794.html">[pycrypto] Verify DSA bytestring signature +</A></li> + <LI> <B>Messages sorted by:</B> + <a href="date.html#793">[ date ]</a> + <a href="thread.html#793">[ thread ]</a> + <a href="subject.html#793">[ subject ]</a> + <a href="author.html#793">[ author ]</a> + </LI> + </UL> + +<hr> +<a href="http://lists.dlitz.net/cgi-bin/mailman/listinfo/pycrypto">More information about the pycrypto +mailing list</a><br> +</body></html> |